bsoeker single or two phase

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mivey

mivey

Senior Member
buffalonymann said:
You're right about one thing, I'm not open minded to anybody's intellectual dishonesty. You've been filed into the snowflake box
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Which says more about you than him.

Gar's posts and history tell his story which indicates his extensive knowledge.

Yours however...
 
B

buffalonymann

Senior Member
Location
NC
Besoeker said:
When L1-N is max positive L2-N is max negative. That's how they work. That's how you get 120V-N on each side and 240 V L1 to L2. Put a scope on them and you will see.
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Well, its not as simple as that. When L1 is positive L2 is negative, N is negative with respect to L1 and at the same time positive with respect to L2. The reason they are in phase is because the current sinusoidal wave for both Lx-N rises and falls simultaneously. We don't need a scope to know this is true, we know that we have a primary coil and when the primary coil current is peak in one direction the secondary L1-N-L2 is peak in the reverse direction.

The only current we see on N connected loads for loads across L1 to N and L2 to N is the imbalance derived from them. This happens because the current through the balanced loads no longer pass through N. A series circuit has been created and the currents for those loads only flow from L1 to L2
 
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buffalonymann

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Location
NC
winnie said:
IMHO if you are going to have an argument about _terminology_ you had better be able to listen to, and understand, different perspectives, rather than simply flat out stating that others are wrong.

This is not physics where ideas are subject to experimental verification; these are words where the meaning is in people's head.

You can explain why different terminology would be better or clearer; and if you do a good job in that explanation you can convince others and change the meaning of the words in their head. But if you simply call people 'snowflakes' they will ignore you.

On the physics: You can clearly define a 180 degree phase difference.

Consider a 2 pole alternator designed with adjustable stator coils, so that you can change the mechanical angle between them. Since there are 360 degrees in a complete rotation you can clearly define 360 degrees of phase relation.

Similarly, in _3_ phase machines we describe the phase angles as 0, 120, and 240 degrees.

Now, in a single frequency pure sine wave situation you cannot distinguish between a true '180' degree phase offset generated by that adjustable alternator and a simple inversion. For purpose of generating a rotating field, such a phase difference (by inversion _or_ 180 degree mechanical rotation) is effectively single phase. Since this simple inversion looks like the 180 degree rotation of the adjustable output, it seems reasonable to use the term 180 degree phase difference.

If you are going to argue that a 180 degree phase difference is meaningless, then I expect you to try to convince the engineering community to describe three phase power using the phase angles 0, 120, 60.

If the adjustable alternator output was somehow not a pure sine wave, then it might be possible to distinguish between the 180 degree rotation of the adjustable coil and a simple inversion.

And just to keep things amusing, in the US, for large residential applications such as apartments, each individual dwelling will be supplied with 2 legs plus neutral of a 208/120 system. This is _called_ single phase because of how it is used, even though there is a real phase difference that can be used to generate a rotating field.

-Jon
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They offered a picture in another thread that inaccurately depicts sine waves for single phase center tapped xfmr; and that's where they're coming up with the 180 phase idea. ITS WRONG - THEY ARE WRONG.

Jon are you suggesting the positive and negative of a battery are 180 degrees out of phase?
 
junkhound

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
buffalonymann said:
I don't need to see somebody's definition of an autotransformer, I know what it is; a single coil that is tapped at a coil ratio for a given voltage output
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Glad to here it, and hear I bin athinkin' an' thot that an AUTOtransformer was a Tesla charger !

BTW, ya being da exspurt, how do the phases of the moon correlate with hexapod phase rotation? Can a phase change material store more energy than a phase shifted capacitor free power scheme/

Inkwirin' minds want to kno ? :weeping::weeping::weeping:

299px-Moon_Phase_Diagram_for_Simple_English_Wikipedia.GIF
 
W

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
buffalonymann said:
They offered a picture in another thread that inaccurately depicts sine waves for single phase center tapped xfmr; and that's where they're coming up with the 180 phase idea. ITS WRONG - THEY ARE WRONG.

Jon are you suggesting the positive and negative of a battery are 180 degrees out of phase?
Click to expand...

Wrong in the physics or wrong in the terminology? I think that you will understand that the physics is understood quite clearly, and that they are using terminology differently from you.

Given that phase angle difference is simply a convenient description of the _time offset_ between two signals, where the time base is a complete cycle of a waveform, it would be quite difficult to describe the phase offset of a DC source. Or are you considering a battery as being AC over long enough time periods?

As I said, an inversion is _not_ a phase difference, but in the case of a single frequency sine wave an inversion is _indistinguishable_ from a true 180 degree phase difference (meaning time offset), and thus it is reasonable to describe an inversion as a 180 degree phase difference.

You conveniently skipped my question about using '240 degrees' to describe one of the phase offsets in 3 phase systems. If a 180 degree phase difference is meaningless, then why don't we use '0, 120, 60' degrees?

-Jon
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180722-0914 EDT

buffalonymann:

For many applications there is a reason you can not use an autotransformer. That reason is the need for isolation.

Do you want a direct conductive path from a 13,000 V line to your 120 V outlet? At my home I have 3 phase delta on the pole, and no neutral. The primary is floating off somewhere, but probably referenced to earth at the substation. I have total isolation from the primary to secondary. My secondary neutral is shared with only my next door neighbor.

.
 
B

buffalonymann

Senior Member
Location
NC
gar said:
180722-0847 EDT

Webester's on-line definition of phase ---

see https://www.merriam-webster.com/dictionary/phase

.
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Look, I made a comment that an engineer told me that single phase xfmr ( we all know what this is, single coil ) produces two phase power ( we all know what two phase power is, generator coils displaced at 90 degrees producing 2 separate voltage and current signals) when center tapped. I made this comment because ingeier, when questioned about his opinions on another subject because upset that I wouldn't just accept his opinion, I want to know the basis for his opinion.

Everybody knew what context the word single, two, and three phase was being used. Ingenier said he believes single phase center tapped power is two phase, and followed by his buddies. Now they're trying to back out of their statements by claiming they meant something else and was using the word phase in another context. These people not only don't understand the subject matter, they're also dishonest.

I am well aware of the definition of 'phase' so lets not make this about that again.
 
I

Ingenieur

Senior Member
Location
Earth
buffalonymann said:
Well, its not as simple as that. When L1 is positive L2 is negative, N is negative with respect to L1 and at the same time positive with respect to L2. The reason they are in phase is because the current sinusoidal wave for both Lx-N rises and falls simultaneously. We don't need a scope to know this is true, we know that we have a primary coil and when the primary coil current is peak in one direction the secondary L1-N-L2 is peak in the reverse direction.

The only current we see on N connected loads for loads across L1 to N and L2 to N is the imbalance derived from them. This happens because the current through the balanced loads no longer pass through N. A series circuit has been created and the currents for those loads only flow from L1 to L2
Click to expand...

120/0
120/180
they are out of phase by 180 deg
you really have no clue
 
I

Ingenieur

Senior Member
Location
Earth
buffalonymann said:
They offered a picture in another thread that inaccurately depicts sine waves for single phase center tapped xfmr; and that's where they're coming up with the 180 phase idea. ITS WRONG - THEY ARE WRONG.

Jon are you suggesting the positive and negative of a battery are 180 degrees out of phase?
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:dunce:

if in phase

L1 = 120/0 = 120 + 0j
L2 = 120/0 = 120 + 0j

v 1-2 = L1 + (-L2) = 120 + 0j + (-120 + 0j) = 0
no 240???
you have exhibited a lack of understanding beyond comprehension

phase, DC, :lol:
 
B

buffalonymann

Senior Member
Location
NC
winnie said:
Wrong in the physics or wrong in the terminology? I think that you will understand that the physics is understood quite clearly, and that they are using terminology differently from you.

Given that phase angle difference is simply a convenient description of the _time offset_ between two signals, where the time base is a complete cycle of a waveform, it would be quite difficult to describe the phase offset of a DC source. Or are you considering a battery as being AC over long enough time periods?

As I said, an inversion is _not_ a phase difference, but in the case of a single frequency sine wave an inversion is _indistinguishable_ from a true 180 degree phase difference (meaning time offset), and thus it is reasonable to describe an inversion as a 180 degree phase difference.

You conveniently skipped my question about using '240 degrees' to describe one of the phase offsets in 3 phase systems. If a 180 degree phase difference is meaningless, then why don't we use '0, 120, 60' degrees?

-Jon
Click to expand...

The depiction inaccurately depicts the scenario. I've described to besoeker how it works, read it. They're starting the connected load going into a negative direction, N is positive with respect to L2 at the same time L1 is positive with respect to L2. those people don't understand this
 
I

Ingenieur

Senior Member
Location
Earth
buffalonymann said:
Look, I made a comment that an engineer told me that single phase xfmr ( we all know what this is, single coil ) produces two phase power ( we all know what two phase power is, generator coils displaced at 90 degrees producing 2 separate voltage and current signals) when center tapped. I made this comment because ingeier, when questioned about his opinions on another subject because upset that I wouldn't just accept his opinion, I want to know the basis for his opinion.

Everybody knew what context the word single, two, and three phase was being used. Ingenier said he believes single phase center tapped power is two phase, and followed by his buddies. Now they're trying to back out of their statements by claiming they meant something else and was using the word phase in another context. These people not only don't understand the subject matter, they're also dishonest.

I am well aware of the definition of 'phase' so lets not make this about that again.
Click to expand...

never said it was 2 ph power, just the opposite
I said it is comprised of 2 signals out of ph, hence 2 phases
you can't comprehend the distinction

as far as your gf scheme
go for it, brilliant idea
 
B

buffalonymann

Senior Member
Location
NC
gar said:
180722-0914 EDT

buffalonymann:

For many applications there is a reason you can not use an autotransformer. That reason is the need for isolation.

Do you want a direct conductive path from a 13,000 V line to your 120 V outlet? At my home I have 3 phase delta on the pole, and no neutral. The primary is floating off somewhere, but probably referenced to earth at the substation. I have total isolation from the primary to secondary. My secondary neutral is shared with only my next door neighbor.

.
Click to expand...

Some primaries are 4160, but that's neither here nor there. I wondered if it was an autotransformer because I see just one primary conductor. If it was, not sure that you could ever see 13kV in the secondary output. Care to propose a scenario where it could?
 
I

Ingenieur

Senior Member
Location
Earth
buffalonymann said:
Some primaries are 4160, but that's neither here nor there. I wondered if it was an autotransformer because I see just one primary conductor. If it was, not sure that you could ever see 13kV in the secondary output. Care to propose a scenario where it could?
Click to expand...

1 conductor? how could i flow?
magic
perhaps there is an external or internal g/n connection?

you realize in an at there is no electrical isolation
common coil, common conductors
 
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